Harvard Forest Research

First steps twoard a trophic ecology of a brown food web at Harvard Forest

Principal Investigator: Michael Kaspari
University of Oklahoma Norman Campus: May 05 2008 - May 05 2009:

Abstract:
The brown (or detrital) food web consists of microbial decomposers, microbivores, and their predators. The process of decomposition emerges from population interactions within brown food webs. Yet little is known about the factors regulating the abundance of these organisms. I propose a pair of experiments--"bottom up" and "top-down"--to explore how nutrient availability and a top predator may serve to shape the abundance microbivores and in turn regulate decomposition. Specifically, "bottom-up" will add 10g N/m2/y of nitrogen, phosphorus, potassium, or a micronutrient treatment (plus controls) to 2x2m plots (n=15, 5 m extents). "Top-down" will increase ant abundance on 1 m2 plots via baiting with sugar water and compared to controls (n=20, 5 m extents). Key response variables include litter depth, decomposition rates of cellulose and maple leaf litter, and the abundance (numbers per 0.25m2) of litter arthropods divided into taxon-based functional groups. "Bottom-up" will run for 1 year, sampling cellulose and leaf litter decomposition at 2 and 12 months, and arthropods at 1 and 2 months. "Top-down" will run for 6 weeks, sampling cellulose decomposition and arthropod abundance after 6 weeks. The project will take place on the Lyford grid.: